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Abstract

Water vapor, as the medium of moisture and latent heat, plays an important role in the Earths various meteorological and climate processes. However, due to its high spatiotemporal variability, precise quantification of water vapor remains a challenge. Ground-based Global Positioning System (GPS) provides a unique tool to measure Integrated Water Vapor (IWV), owing to its advantages of high accuracy, high temporal resolution, and all-weather condition availability. Though tens of thousands of ground-based GPS stations all over the world have been put into operation in recent years, only hundreds of them were used to retrieve IWV in most previous studies. A GPS IWV dataset with densified stations around the world is still lacking. The Nevada Geodetic Laboratory (NGL) has been routinely collecting and processing more than 10,000 global GPS stations, and thus provide us an opportunity to obtain the global IWV with densified GPS networks. In this work, we used the GPS Zenith Total Delay (ZTD) provided by NGL to retrieve the global IWV in 2020. The pressure level products of the latest fifth generation of ECMWF atmospheric reanalysis (ERA5) was also employed in the retrieval of GPS IWV. The GPS and ERA5 IWV estimates were then compared.